Fe-Si-B-P-C-Cu高Bs纳米晶软磁合金的结构调控及对软磁性能和弯折韧性的影响机理研究

High Fe concentration Nanocrystalline alloys have been discovered as a promising soft magnetic material in our previous work. However, the extremely brittle nature for the nanocrystalline Fe-based soft magnetic alloys has generally been recognized to be the most serious disadvantage which limited their engineering application. The present proposal is devoted to a comprehensive study of the alloying effects of transition metals and metalloid element on the thermal stability, microstructural evolution, soft-magnetic properties and bending ductility of nanocrystalline FeSiBPCCu alloys were systematically investigated. First, the composition-amorphous structure formation-magnetic property correlation is to be clarified in the amorphous alloy system, from which the optimal alloy composition is proposed. The crystallization behaviors of these precursor amorphous alloys are then studied to reveal the underlying mechanism of minor alloying on nanodecomposition, and the corresponding nanocrystallization model will be put forth. Finally, the influence of the various control parameters of heat treatment on changing the crystallization counterparts, the microstructure length scale and hence the magnetic properties and bending ductility of the nanocrystalline alloys will be investigated, from which the correlation of composition-microstructure-soft magnetic property-bending ductility is to be established for the nanocrystalline soft magnetic alloys. The present study would provide theoretically useful guidelines and candidate materials for the development of industrially applicable nanocrystalline soft magnetic alloys with high saturation magnetization.

高Bs纳米晶软磁合金在退火得到非晶/纳米晶双相复合结构后，软磁性能优化的同时都不可避免的呈现弯折脆性，这成为该类材料在节能高效电机等高端领域应用推广所面临的瓶颈问题。本项目拟以高Fe浓度Fe-Si-B-P-C-Cu系合金为对象，在我们前期工作的基础上，研究微量过渡金属添加和类金属元素的配比调节对合金的热稳定性、非晶形成能力、软磁性能和弯折韧性的影响规律，澄清合金元素影响其热稳定性和非晶形成能力的机制。系统研究不同合金元素对 Fe-Si-B-P-C-Cu非晶晶化行为的影响，结合结构表征及其相变动力学分析等手段，澄清它们影响其晶化行为的机制，发展软磁纳米晶形成理论。研究热处理工艺参数对合金组织结构、磁性能和弯折韧性的影响规律，揭示合金性能与其成分、组织结构的相关性，阐明合金元素影响其软磁性能和弯折韧性的机理。为发展工业实用化的高性能纳米软磁合金提供理论依据和工艺技术支撑。

由非晶前驱体退火热处理后形成的高Fe含量Fe-Si-B-P-Cu系纳米晶合金具有高饱和磁感应强度（Bs）、低矫顽力（Hc）和高磁导率（μe）等优良的软磁性能，已应用于变压器、电抗器、互感器等电子电力器件中。然而，经退火处理后形成的该系纳米晶合金脆性较高，且获得较高的Bs和较低Hc的热处理工艺（热处理温度、时间等）窗口较窄，其软磁性能对淬态前驱体合金的结构较敏感，不利于其在电子电力等领域的更广泛应用。针对上述问题，本论文通过调整经熔体旋淬法快速凝固制备的淬态Fe-Si-B-P-Cu系非晶前驱体合金的成分和热处理方式及工艺参数，调控了所获得的纳米晶合金的结构和性能，系统研究了调整合金的成分和快速退火工艺对高Fe含量Fe-Si-B-P-Cu系纳米晶合金微观组织结构、软磁性能和退火脆性的影响，阐明了该系纳米晶合金成分-热处理工艺参数-结构-性能之间的关联及机理。发现采用快速退火（升温速率为100 °C/s及以上）的热处理温度窗口较宽，所制备的Fe-Si-B-P-Cu系纳米晶合金兼具高Bs和低Hc等优异软磁性能和较低退火脆性，且其对淬态前驱体合金结构不敏感。.通过采用适当的快速退火热处理工艺及调整Fe-Si-B-P-Cu系前驱体合金成分可以有效调控所形成的纳米晶合金的结构，使合金的非晶基体中析出高体积分数且尺寸均匀细小的α-Fe，获得兼具优异软磁性能和低退火脆性的Fe-Si-B-P-Cu系纳米晶合金。以快速凝固Fe-Si-B-P-Cu系合金为前驱体，对其进行快速退火制备纳米晶合金的Top区间较宽，且降低了所形成的纳米晶合金的软磁性能对于淬态前驱体合金的结构敏感性，有利于其工业化生产。本论文的研究结果可以为发展具有实际应用价值的新型高性能Fe基纳米晶软磁合金提供实验科学依据和工艺技术支撑。